Total recovery core catcher



Nov. 25, 1969 F. CLYNCH TOTAL RECOVERY CORE CATCHER Filed Jan. 4, 1968 FIG.

INVENTOR. FRANK CLYNCH BY %4/ ATTORNEY United States Patent 3,480,093 TOTAL RECOVERY CORE CATCHER Frank Clynch, Ponca City, Okla., assignor to Continental Oil Company, Ponca City, Okla., a corporation of Delaware Filed Jan. 4, 1968, Ser. No. 695,741 Int. Cl. E21b 9/20, 25/00 US. Cl. 175-58 5 Claims ABSTRACT OF THE DISCLOSURE A core catcher for collecting liquid, semi-solid or solid cores from a bore hole comprising a hollow housing with an elastic expandable liner positioned inside the housing, said liner being capable of forming a total seal against liquid flow upon being expanded by the application of gas pressure between the interior wall of said housing and said liner.

This invention relates to core drilling and more particularly to devices for removing soft or liquid containing cores.

Soft or friable cores such as sand, coal or the like are diflicult to hold and extract with known hollow core barrels due to the cores disintegrating and crumbling. Core catchers using a wedging action on the core and positioned at the bottom of an associated core barrel are well known. Collapsing fingers to cut off and hold soft cores have also been used. Also it is known to utilize a core catcher having an inner and outer tube with the inner tube being constructed of pliable material which can be collapsed by applying hydraulic force so as to partially seal off the space occupied by the core and in addition a filling of dough-like material has been used in conjunction with said pliable material to aid in sealing oil and retaining the semi-solid core.

In accordance with this invention a core catcher is provided which is capable of obtaining a liquid or semi-solid core sample and which is also capable of being used repeatedly. This invention comprises a housing having a passageway therethrough, an elastic liner positioned inside the housing and secured to said housing so that a gas source can be ,used to expand the elastic liner to form a seal against liquid flow through said housing. Gas may be applied through a separate line for shallow operations, but for deeper operations the standard drill pipe can be equipped with a gas channel to provide the gas necessary to expand said elastic liner. Upon removal of said gas pressure the elastic liner returns to its original position and a new core sample can be obtained.

The invention is illustrated in the accompanying drawings in which:

FIG. 1 is a view of the core catcher, partly in section, and connected to a section of drill pipe having a gas passageway therein. 7

FIG. 2 is a view taken along the lines 22 of FIG. 1 and showing the elastic liner in its expanded position.

Referring to FIG. 1 of the drawings, the total recovery core catcher 11 is attached to a section of drill pipe 23 at one end and to a core cutting bit 33 at the other end. Inside of the housing 12 there is a rigid liner 13, and inside said rigid liner is a tubular elastic liner 15 having an overlapping lip at its upper and lower ends which is held in place by retaining ring 17 and threaded ring 19'. Both the drill pipe 23 and the housing 12 are equipped with a gas passageway 21. An O-ring 31 is positioned in a channel of said rigid liner 13 to prevent gas leakage between rigid liner 13 and the interior wall of housing 12.

In FIG. 2 of the drawings the elastic liner 15 is shown in an expanded position while under gas pressure exerted 3,480,093 Patented Nov. 25, 1969 ice through passageway 21. The inwardly expanded elastic liner 15 completely closes oflf the passageway through the center of housing 12.

In the operation of the invention a core sample is cut in the normal manner. After the core sample is positioned inside the elastic liner 15, gas pressure is applied through gas passageway 21 to expand elastic liner 15 inwardly at its mid-portion to seal off the passageway through the center of housing 12. To insure that gas pressure sufficient to keep elastic liner 15 expanded to maintain a seal against liquid flow through the center of housing 12 and thereby retaining said core sample regardless of its viscosity, a standard check valve 29 can be installed in gas passageway 21. This check valve will also enable the housing 12, containing said core sample, to be removed from the bore hole without losing said core sample. For shallow drilling operations the gas pressure can be applied through a separate line from the surface to the total recovery core catcher 11; however, for deeper operations a gas passageway 21 as shown in FIG. 1 is preferred. In the preferred embodiment the rigid liner 13 is equipped with a gas passageway 25 in communication with the gas passageway 21 of the housing 12 with said gas passageway 25 terminating in a gas port 27. In the preferred embodiment a plurality of gas ports 27 are used to insure that the passageway through the center of housing 12 will be completely sealed to prevent the liquid part of said core sample from flowing out of said housing.

The elastic liner can be made of any material which is impervious to gas and which will maintain its elasticity under the conditions present in core drilling operations. An example of a material suitable as said elastic liner is rubber.

The rigid liner can be made of any material which will remain rigid under the conditions present in core drilling operations. Examples of materials suitable as said rigid liner are metals, alloys, and rigid plastics.

It will be evident that various details of construction and operation will be modified without departing from the invention as defined in the following claims.

What is claimed is:

1. A total recovery core catcher comprising:

(1) a tubular housing having a passageway therethrough;

(2) a tubular elastic liner positioned inside said hous- (3) means for securing said tubular elastic liner to said housing at the upper and lower extremes of said tubular elastic liner;

(4) means for expanding the middle portion of said elastic liner inwardly to seal said passageway against liquid flow; and

(5) means for returning said expanded portion of said elastic liner to its original position.

2. A total recovery core catcher as claimed in claim 1 wherein said elastic liner is made of rubber.

3. A total recovery core catcher as claimed in claim 1 wherein said means for securing said elastic liner to said housing comprises a rigid liner having a channel for receiving an upper and lower lip of said elastic liner and in which said elastic liner is placed prior to inserting said rigid liner into said housing and a retaining member for holding said rigid liner in place in said housing.

4. A total recovery core catcher as claimed in claim 1 wherein said means for expanding said elastic liner comprises the housing of claim 1 having a gas passageway therein in communication with a gas source and with the outermost wall of said-elastic liner for the passage of a gas sufiicient to expand said liner inwardly to form a total seal against liquid flow through said first passageway of claim 1.

3 4 5. A method of obtaining a liquid containing core (f) recovering said liquid containing core sample from sample from a bore hole comprising: said core catcher.

(a) placing a core catcher having an elastic liner into Said bore. hole; References Cited (b) cutting a liquid containing core sample; 5 UNITED STATES PATENTS (c) filling said core catcher with said liquid containing 2 93 1 7 /1959 Johnson 1 2 X Core p 2,927,776 3/1960 Hildebrandt 175245 X (d) expanding said elastic liner inwardly at its mid- 3,349 57 10 19 7 Hildebrandt 175 250 portion seal to retain said liquid containing core Sample; 10 NILE C. BYERS, JR., Prlmary Examiner (e) removing said core catcher from said bore hole; US. Cl. X.R.

and 75-250; l662l2 U.S. PATENT OFFICE United States Patent Office Certificate of Correction Patent No. 3,480,093 Dated Nov. 25, 1969 It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Claim 5, sub-section (d) "to form a total" has been omitted after "portion.

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